THE JOB of the theater is to seize an audience and lift it to new heights of understanding.

But there's a hitch. To perform this amazing feat, one must first have an audience present and accounted for. A theoretical model exists for accomplishing this. The performance is announced and attendance is, to begin with, rather aggressively solicited. A few people, intrigued by one or another feature of the announcement, show up. If they like what they see (and are willing to admit it), they report that fact -- some of us through more public channels than others. The audience grows. And before long we are dealing with a phenomenon that is totally Out of control, like some prehistoric beast that sprang from the sewers to ravage a city.

When all this fails to happen, it is usually for the best of reasons: The work itself, the mainspring of this wondrous mechanism, lacks the necessary drive. But there are other barriers that occasionally stand between a play and its audience.

"Charlie and Algernon," the Folger Theatre/Kennedy Center co-production that went to Broadway with high hopes only to close after two weeks, combined a serious issue (human tinkering with the human brain), a baldly anti-medical bias, and a large injection of song-and-dance piczazz. As a result, it suffered from a niche problem. It didn't fit into any known grooves. And the producers' decision to call it "A Very Special Musical" (beneath the title) hardly helped matters. It only encouraged critics and audiences to think of the show as a serious story of mental retardation rather than the science-fiction fable it was.

"Charlie and Algernon" was conceived on approximately the same primitive level of sentimentality and morality as "Annie) or Barnum." But the same qualities that served those utterly frivolous shows so well came in for a royal pasting from the press when "Charlie" arrived on Broadway. Just the same, the producers had grounds for thinking they had an "Audience show" on their hands. "Charlie" had been a hit twice over at the Kennedy Center, where it had generated standing ovations after almost every performance -- and that remarkable state of affairs had continued (despite the high percentage of empty seats) through the New York previews.

But in Washington, "Charlie" had begun life with a receptive base audience -- the Folger Theatre Group's subscribers. The good word of mouth that helped the show here never had a chance to happen in New York, where it opened with no "names" and no advance sale. With money and patience, "Charlie" might have overcome all the obstacles, found its audience and become a hit -- but who could afford such a gamble? The producers had already sunk about $900,000 into the show, and they decided, understandably, to leave it at that.

"Joseph and His Technicolor Dreamcoat's" Extraordinary, recurring success is the flip aside of this coin. Here, a show with minimal wit, imagination and novelty (a show that is very possibly something of an embarrassment to Andrew Lloyd Weber and Tim Rice, who wrote it when they were very young) has filled up the Hartke, Olney and Ford's theaters over the last three years precisely because it is so easy to describe and addressed to such an easily described audience -- the Biblical soft-rock set.

The creators of "Fiddler on the Roof" aren't complaining about their audiences, so far as I know -- not after eight years on Broadway, visits to an astounding 75 countries and 50 foreign-language cast albums.

And the Warner Theater was full up when I looked in on the show two weeks ago. Full . . . but, then again, not quite full. In the entire orchestra (roughly 1,000 occupied seats), two black faces were countable. Last spring, by contrast, the audiences at the Warner's "Ain't Misbehavin'," with a black cast performing songs by a black songwriter, were close to evenly mixed, white and black.

The saga of Tevye and his daughters, the happy/miserable town of Anataveka, the constant threat of a program, the Jerry Bock/Sheldon Harnick songs, the Sholom Alecheim/Joseph Stein story -- are these somehow whites-only ingredients? Hard to believe. It is easier to believe that theatergoing remains largely a white (and affluent) habit in Washington, and that a Jewish subject remains a particular turn-off to black audiences.

"Fiddler" has long since transcended the status of a "Jewish musical," so it seems mildly increadible now that in 1963, when Jerome Robbins agreed to direct the show, he said it was a labor of ethnic loyalty for which he did not expect great financial reward. What he failed to realize was the show-business analogue to the principle of less is more: Namely, narrower-is-wider.

Washington's current movie fare offers a vivid illustration of this principle. "The Chant of Jimmy Blacksmith" is a stunningly photographed movie with a harrowing story, a huge cast, extraordinary turn-of-the-century locations and violence like you've never seen -- honest violence, made neither less nor more of than the story demands. The story concerns a young, industrious Australian aborigine who labors as a fence-builder and Uncle-tom-of-all-trades until, one day, he can no longer live with white exploitation or his own complicity in it. So he "declares war."

Among its other virtues, this movie knows what a human wound looks like and how the body responds to being shot or bludgeoned or axed. And the subject matter -- colonialism, race, class struggle, ambition, the containment of anger and the compromising of human dignity -- is hardly narrow of esoteric stuff. There is no good reason why "Jimmy Blacksmith" shouldn't be a large box-office hit.

But there are plenty of bad reasons. "Jimmy Blacksmith" will vacate the Avalon Theater this Friday, after three weeks of middling business. A Circle Theatres official says "Jimmy Blacksmith" did neither worse nor better than expected, considering its status as a "specialty picture" with a disturbing amount of violence. The movie has played in New York and San Franciso too, but it took Daniel Talbot of New Yorker Films, the movie's distributor, a full year to engineer even that modest release.

Meanwhile, "My Brilliant Career," another Australian movie, has become a startling, nationwide success, despite what seems, at first glance, to be far less commercial subject matter. (The heroine is an aspiring writer -- need we say more?) The reason is that "My Brilliant Career" fits into an established, definable niche. It is what used to be called an "art film" (a very well-made one too), and everything about it -- title, place of origin, subject matter -- accurately advertises the whole. It is also what used to be called a "women's picture." There is an audience that watches for such movies, and passes the word. By contrast, "Jimmy Blacksmith" refuses to fit into any recognizeable movie-making tradition, and its title, if it suggests anything, suggests an old Disney movie with Sal Mineo as an Indian boy grooming his pet burro for the Kentucky Derby.

For as long as there has been art, there has ben a marketplace for it, and powerful disincentives to innovation. The carrots grow ever-sweeter, the sticks ever-harder. The wonder is that, once in a blue-moon, the old engines spew out something drastically different from all that has come before -- an artist stares his audience in the eye and, as Vladimir Nabokov has put it, "recombines" the world down to "its very atoms."

And what are the rewards for doing so? "Up a trackless slope climbs the master artist," Nabokov writers, "and at the top, on a windy ridge, whom do you think he meets? The panting and happy reader, and there they spontaneously embrace and are linked forever . . ."